Over-the-Wire-Valvulotomes

ABSTRACT

Over-the-wire self-sizing, self-centering valvulotomes sufficiently designed to cut valves through a wide range of vein diameters and adjust to the internal diameter of a vein as the valvulotome is being drawn through the vessel, and methods of use thereof during certain medical procedures that involve splitting valves, are disclosed herein. In an embodiment, an over-the-wire valvulotome includes a catheter having a proximal end, a distal end, and a longitudinal axis therebetween, wherein a first portion of a plurality of cutting tools engage the catheter at the distal end, and wherein an actuation mechanism engages the catheter at the proximal end; a retainer for temporarily shielding a second portion of the plurality of cutting tools, wherein the second portion includes cutting blades; and a sheath slidably moveable over the plurality of cutting blades, wherein the catheter and the retainer have internal diameters configured for passing over a guidewire.

RELATED APPLICATIONS

This application is a continuation patent application of U.S.application Ser. No. 13/908,469, filed on Jun. 3, 2013, which is acontinuation patent application of U.S. application Ser. No. 13/166,137,filed on Jun. 22, 2011, now U.S. Pat. No. 8,491,614, which claims thebenefit of and priority to U.S. Provisional Application No. 61/357,347,filed Jun. 22, 2010, the entirety of these applications are herebyincorporated herein by reference for the teachings therein.

FIELD

The presently disclosed embodiments relate to blood vessel instrumentswith self-centering structure and more particularly to over-the-wirevalvulotomes and methods of use thereof.

BACKGROUND

Peripheral vascular disease (PVD), also known as peripheral arterydisease (PAD) or peripheral artery occlusive disease (PAOD), includesall diseases caused by the obstruction of large arteries in the arms andlegs; and it also includes a subset of diseases classified asmicrovascular diseases resulting from episodal narrowing of the arteries(raynauds), or widening thereof (erythromelalgia) i.e. vascular spasms.PVD can result from atherosclerosis, inflammatory processes leading tostenosis, an embolism, or thrombus formation. PVD causes either acute orchronic ischemia (lack of blood supply), typically of the legs.

Some patients suffering from PVD present to their surgeon withinsufficient blood flow in their lower extremities. This diseasemanifests itself along a spectrum: from discomfort after walking togangrenous toes and/or feet. Surgical bypass using the saphenous vein isthe gold standard of treatment for severe PVD. The in situ method ofsurgical bypass involves leaving the saphenous vein in its native bedand cutting the one-way check valves (a procedure known as avalvulotomy) which would normally insure venous blood flow towards theheart. Without these valves the surgeon is able to utilize the vein asan arterial conduit, in effect “arterializing” the vein. Valvulotomiesare typically performed using valvulotomes.

SUMMARY

According to aspects illustrated herein, there is disclosedover-the-wire (“OTW”) self-centering and self-sizing valvulotomes. In anembodiment, an OTW valvulotome of the present disclosure hasself-sizing, self-centering cutting devices with self-centeringcapabilities for use within a tubular passageway.

According to aspects illustrated herein, there is disclosed an OTWself-sizing, self-centering valvulotome that includes a catheter havinga proximal end, a distal end, and a longitudinal axis therebetween,wherein a first portion of a plurality of cutting tools engage thecatheter at the distal end, and wherein an actuation mechanism engagesthe catheter at the proximal end; a retainer for temporarily shielding asecond portion of the plurality of cutting tools, wherein the secondportion includes cutting blades; and a sheath slidably moveable over theplurality of cutting blades, wherein the catheter and the retainer haveinternal diameters configured for passing over a guidewire.

According to aspects illustrated herein, there is disclosed an OTWself-sizing, self-centering valvulotome that includes a protectivesheath having a lumen; a catheter having a catheter lumen, a distalportion, and a proximal portion, the catheter being partly and slidablydisposed within the protective sheath; a retainer having a retainerlumen and at least four slots, the retainer fixedly engaging the distalportion of the catheter so as to provide a continuous internal channelfor a guidewire; a self-sizing, self-centering cutting unit having atleast four cutting tools, wherein each cutting tool comprises: a firstend fixedly engaged to the distal portion of the catheter; a second endmoveably positioned within and guided by the slot of the retainer, thesecond end having a cutting blade with a recessed cutting edge; aself-sizing, self-centering resilient arm connecting the first end withthe second end; and a radially bent shaped neck transitioning betweenthe arm and the second end, the neck sufficiently designed toaccommodate an outer circumference of the catheter; and a dual-purposecontrol mechanism attached to the protective sheath's proximal end andallowing the passage therethrough of the catheter, such that a user ofthe valvulotome can sheathe and unsheathe the cutting tools by slidingthe catheter distally or proximally relative to the protective sheath,or slide the sheath distally or proximally relative to the catheter.

According to aspects illustrated herein, there is disclosed a method ofpreparing a vein for a valvulotomy procedure using an OTW self-sizing,self-centering valvulotome of the present disclosure.

According to aspects illustrated herein, there is disclosed a method ofpreparing a vein for in situ arterial bypass surgery using an OTWself-sizing, self-centering valvulotome of the present disclosure.

According to aspects illustrated herein, there is disclosed a method ofperforming a valvulotomy procedure that includes inserting anover-the-wire self-sizing, self-centering valvulotome over a guidewireand into the vein at a distal access point, wherein the valvulotomecomprises: a catheter having a proximal end, a distal end, and alongitudinal axis therebetween, wherein a first portion of a pluralityof cutting tools engage the catheter at the distal end, and wherein anactuation mechanism engages the catheter at the proximal end; a retainerfor temporarily shielding a second portion of the plurality of cuttingtools, wherein the second portion includes cutting blades; and a sheathslidably moveable over the plurality of cutting blades; feeding thevalvulotome into the vein with the cutting unit sheathed, until thecutting unit is past a most proximal valve in the vein; manipulating theactuation mechanism to unsheath the cutting unit to release the cuttingblades; and withdrawing the valvulotome from the vein, thereby severingeach valve in the vein.

BRIEF DESCRIPTION OF THE DRAWINGS

The presently disclosed embodiments will be further explained withreference to the attached drawings, wherein like structures are referredto by like numerals throughout the several views. The drawings shown arenot necessarily to scale, with emphasis instead generally being placedupon illustrating the principles of the presently disclosed embodiments.

FIGS. 1A and 1B show perspective cutaway views of an embodiment of anover-the-wire (OTW) valvulotome of the present disclosure in the normalposition. FIG. 1A shows the distal portion of the OTW valvulotome. FIG.1B shows the proximal portion of the OTW valvulotome;

FIGS. 2A and 2B show perspective views of the OTW valvulotome of FIGS.1A and 1B in the abandoned position. FIG. 2A shows the distal portion ofthe OTW valvulotome. FIG. 2B shows the proximal portion of the OTWvalvulotome;

FIG. 3 shows a perspective exploded view of an embodiment of some of thecomponents of a distal portion of the OTW valvulotome of FIG. 1A;

FIG. 4 shows a perspective view of an embodiment of a cutting unit ofthe OTW valvulotome of FIG. 1A in the normal position;

FIG. 5 shows a perspective view of an embodiment of a retainer of theOTW valvulotome of FIG. 1A;

FIGS. 6A and 6B show perspective views of the distal portion of the OTWvalvulotome of FIG. 1A in the normal and abandon positions of use,respectively;

FIG. 7 shows a cutaway view along line 7-7 in FIG. 6B;

FIG. 8 shows a perspective exploded view of the OTW valvulotome of FIGS.1A and 2A with an alternative embodiment of a retainer at the distal endthereof;

FIG. 9 shows a perspective exploded view of the OTW valvulotome of FIGS.1A and 2A with an alternative embodiment of a retainer at the distal endthereof;

FIG. 10 shows a perspective view of an alternative embodiment of acombination retainer/atraumatic tip for use at the distal end of the OTWvalvulotome of FIGS. 1A and 2A.

While the above-identified drawings set forth presently disclosedembodiments, other embodiments are also contemplated, as noted in thediscussion. This disclosure presents illustrative embodiments by way ofrepresentation and not limitation. Numerous other modifications andembodiments can be devised by those skilled in the art which fall withinthe scope and spirit of the principles of the presently disclosedembodiments.

DETAILED DESCRIPTION

The embodiments disclosed herein relate to over-the-wire (“OTW”)self-sizing, self-centering valvulotomes and methods of use thereofduring certain medical procedures that involve splitting valves. In anembodiment, an OTW valvulotome of the present disclosure is used duringin situ arterial bypass surgery. In an embodiment, an OTW valvulotome ofthe present disclosure is used during a periphery arterial bypasssurgery. In an embodiment, an OTW valvulotome of the present disclosureis used during a coronary arterial bypass surgery. In an embodiment, anOTW valvulotome of the present disclosure is used during anarteriovenous fistula (AV fistula) procedure, for example to allowaccess to the vascular system for hemodialysis.

In an embodiment, an OTW valvulotome of the present disclosure is usedfor performing minimally-invasive valvulotomy. In an embodiment, an OTWvalvulotome of the present disclosure is sufficiently sized and shapedto be used in a valvulotomy procedure. In an embodiment, an OTWvalvulotome of the present disclosure is sufficiently sized and shapedto be used in an in situ arterial bypass surgery down the entire leg ofa patient. In an embodiment, an OTW valvulotome of the presentdisclosure is sufficiently sized and shaped to be used in an in situarterial bypass surgery down a portion of the leg of a patient, forexample, in a surgery where the surgeon has to harvest only above orbelow the knee. In an embodiment, an OTW valvulotome of the presentdisclosure can effectively, efficiently, and automatically disablevalves, yet not damage the vein wall. In an embodiment, an OTWvalvulotome of the present disclosure can cut valves through a widerange of vein diameters, thus one size cutting unit allows for effectivevalve disruption through a wide range of vein diameters. In anembodiment, an OTW valvulotome of the present disclosure can be movedfreely up or down the vein during the valve disruption process, allowingmultiple passes at each valve site without removing the valvulotome.

In an embodiment, an OTW valvulotome of the present disclosure is asterile, biocompatible, hemostatic, disposable device that lyses venousvalves for distal bypass and other procedures. In an embodiment, an OTWvalvulotome of the present disclosure is sufficiently designed forsingle use and is disposable.

In an embodiment, an OTW valvulotome of the present disclosure issufficiently designed to include centering hoops that keep thevalvulotome centered in a vein and prevent the valve-cutting blades fromdamaging the vein wall. In an embodiment, the size of the centeringhoops and blades adjusts to the internal diameter of a vein as thevalvulotome is being drawn through the vessel. In an embodiment, an OTWvalvulotome of the present disclosure is sufficiently designed to allowa plurality of cutting blades to automatically bias against a vein wall.In an embodiment, an OTW valvulotome of the present disclosure includesa safety feature whereby the cutting blades can be retracted or sheathedto protect a vein wall if the need arises. In an embodiment, an OTWvalvulotome of the present disclosure is used with a guidewire to assistin the insertion, navigation and positioning of the valvulotome in avein. In an embodiment, use of a guidewire in conjunction with an OTWvalvulotome of the present disclosure results in increased safety forinitial passage of the valvulotome through a vein. In an embodiment, useof a guidewire in conjunction with an OTW valvulotome of the presentdisclosure results in the ability to confirm valvulotome location via animaging technique. In an embodiment, use of a guidewire in conjunctionwith an OTW valvulotome of the present disclosure results in increasespeed and safety when passing the valvulotome multiple times over aguidewire through a vein.

In an embodiment, an OTW valvulotome of the present disclosure has someinherent radiopacity due to some of the components of the OTWvalvulotome being fabricated from metal materials and the associatedguidewire which can be radiopaque. In an embodiment, an OTW valvulotomeof the present disclosure is sufficiently designed to allow for fluidinsertion or removal at or near the cutting unit. In an embodiment, anOTW valvulotome of the present disclosure is sufficiently designed toallow for fluid pressure monitoring at the site of fluid insertion orremoval by a surgeon during the procedure. An OTW valvulotome of thepresent disclosure may likewise be used in other, non-surgicalapplications that require a self-centering device. The inner channel ofan OTW valvulotome of the present disclosure can be used for theinsertion of other endovascular instruments into the vein for surgicalbypass or diagnosis (e.g. tributary ligation, anastomosis, biopsy,endoscopy, etc.).

FIGS. 1A, 1B, 2A, and 2B show perspective views of an embodiment of anOTW valvulotome 100 of the present disclosure in normal (FIGS. 1A-1B)and abandon (FIGS. 2A-2B) positions of use. The OTW valvulotome 100includes a catheter 140 having a distal portion (FIGS. 1A and 2A) with aself-sizing, self-centering cutting unit 120, a proximal portion (FIGS.1B and 2B) terminating in a control mechanism 180, and a longitudinalaxis therebetween. The catheter 140 is partly and slidably disposedwithin a protective sheath 170. In an embodiment, the sheath 170 isremovable. In an embodiment, the sheath 170 is a thin plastic tubularmember which is a loose sliding fit on the outer diameter of thecatheter 140. In an embodiment, the sheath 170 is manufactured from apolytetrafluoroethylene material. In an embodiment, the sheath 170 ismanufactured from a thermoplastic material. In an embodiment, the sheath170 covers the cutting unit 120 during insertion (FIG. 2A), allowing forsmooth advancement to the proximal anastomosis. In an embodiment, thesheath 170 includes at least one safety marking 175 which can help alerta user when the cutting portion of a cutting blade is nearing the exitpoint of the vessel. As illustrated in FIG. 2A, the cutting unit 120 isin a sheathed position, completely encased by the sheath 170. When thesheath 170 is slid, a plurality of radially mounted, retractable cuttingblades of the cutting unit 120 are in an open “normal” position, asillustrated in FIG. 1A.

As illustrated in FIGS. 1B and 2B, in an embodiment, the controlmechanism 180 is a dual-purpose control mechanism attached to the sheath170. In an embodiment, the control mechanism 180 is sufficientlydesigned to serve as a handle for a user. The control mechanism 180 maycomprise a T-valve segment 182, having an access port 183 and a terminalend 184, disposed partly within the proximal end of the sheath 170, theterminal end of the T-valve segment 182 being adapted to allowengagement of a pull handle 185 affixed to the proximal end of thecatheter 140. In an embodiment, a tube stiffener is positioned over thecatheter 140 proximal to the T-valve segment 182. In an embodiment, thecontrol mechanism 180 is sufficiently designed to expand/contract theplurality of cutting blades of the cutting unit 120 as a user actuatesthe mechanism.

When the pull handle 185 engages the terminal end of the T-valve segment182 (FIG. 1B), a fluid-tight seal is created, allowing the introductionof a diagnostic (for example, saline) or therapeutic fluid (for example,anticoagulant solutions) to the distal end of the sheath 170 via theT-valve access port 183 and the lumen of the sheath 170. The sheath 170serves as a fluid conduit, allowing irrigation with heparinized salineand/or continuous pressure monitoring during a valvulotomy procedure.The safety stripe 175 located on the sheath 170 of the OTW valvulotome100 can be about 3.5 cm beyond the distal end of the sheath 170. Seeingthe safety stripe 175 upon withdrawal serves as a warning that the useris near the end of the OTW valvulotome 100, and that the cutting unit120 should be closed to stow the cutting blades for final withdrawalfrom the vein. The T-valve access port 183 accepts a syringe, which canbe attached to a syringe holding, for example, heparinized saline. Thoseskilled in the art will recognize that segment 182 can be any size orshape (for example, a Y-valve with multiple access ports) and still bewithin the scope and spirit of the present disclosure. Those skilled inthe art will recognize that pull handle 185 can be any size and shape aslong as the handle is configured to actuate and deploy the cuttingblades of the cutting unit.

FIG. 3 shows a perspective exploded view of an embodiment of some of thecomponents of a distal portion of the OTW valvulotome 100 of FIG. 1A. Asillustrated in FIG. 3, the distal end of the catheter 140 engages aproximal end profile 133 of a retainer 132. A distal end profile 131 ofthe retainer 132 engages a proximal end of a hypotube 122, and a distalend of the hypotube 122 can be partially or completely disposed withinan atraumatic tip 112. In an embodiment, the atraumatic tip 112 isfabricated from one part. In an embodiment, the atraumatic tip 112 isfabricated from more than one part, for example, a cap and a tip. In anembodiment, the atraumatic tip 112 is a machined plastic part. In anembodiment, the atraumatic tip 112 is a machined metal part. In anembodiment, the hypotube 122 is press-fitted into the the atraumatic tip112. The distal end of the OTW valvulotome 100 of the present disclosureis sufficiently designed to be atraumatically introduced into a vessel.

In an embodiment, the atraumatic tip 112, the catheter 140, the retainer132, and the hypotube 122 are separate pieces that can be seam-welded,face-welded, butt-welded, spot-welded, soldered, adhesive bonded,chemically bonded or mechanically fastened together. The catheter 140,the retainer 132, and the hypotube 122, when engaged, form a continuousinternal channel, allowing the OTW valvulotome 100 to be advanced over aguidewire. In an embodiment, the internal channel amounts to half thecross-sectional area of the distal portion of the OTW valvulotome 100,without a substantial change to the outer diameter. The guidewire wouldrun coaxially through the catheter 140, the retainer 132, the hypotube122 and the atraumatic tip 112.

In an embodiment, the catheter 140 is a multilayered tube, manufacturedby extruding a tube, braiding or coiling over the tube with wire orpolymer, and extruding an outer jacket over the braid or coil. The tubemight then be drawn through a hot die to fuse the different layerstogether. In an embodiment, the catheter 140 includes at least a portionthat is flexible. In an embodiment, the entire catheter 140 is flexible.In an embodiment, the catheter 140 includes at least a portion that isrigid. In an embodiment, the catheter 140 includes at least a portionhaving laser-cut side slots (FIG. 3). In an embodiment, the catheter 140is a straight extension. In an embodiment, the catheter 140 is a curvedextension. In an embodiment, the catheter 140 is manufactured from ametal material. In an embodiment, the catheter 140 is manufactured froma nitinol material. In an embodiment, the catheter 140 is manufacturedfrom a stainless steel material. In an embodiment, the stainless steelmaterial has multiple small sections of the wall cut away to increasethe flexibility of the catheter 140. In an embodiment, the catheter 140is a naked braid In an embodiment, the catheter 140 is non-braided ornon-coiled. In an embodiment, the catheter 140 is manufactured from athin material configured to maintain strength and pushability byextruding a braid or coil with a plastic coating/extrusion over the top.

FIG. 4 shows a perspective view of an embodiment of a cutting unit 120of the OTW valvulotome 100 of FIG. 1A in the normal position. Cuttingunit 120 generally includes four self-centering, self-sizing cuttingtools 160 each having a first, attached end 168 equally radially mountedon the distal portion of the catheter 140, a second, unattached end 162(visible in FIGS. 6A and 6B) with a cutting blade 164 having a recessedcutting edge 165, and a self-sizing, self-centering arm/hoop 166. Thefirst ends 168 of each of the cutting tools 160 fixedly engage a distalportion of the catheter 140. The cutting blades 164 of each of thecutting tools 160 are temporarily shielded by the retainer 132 duringentry and removal of the valvulotome 100. Each cutting blade 164 has anupper, non-cutting outermost edge shielding the cutting edge 165disposed inwardly therefrom relative to the catheter 140 such that thecutting edge 165 is oriented toward the proximal end of the OTWvalvulotome 100. During use, the valvulotome 100 is advanced through thelength of a vein in the closed position, then opened and retracted backthrough the length of the vein to cut the valves.

In an embodiment, the self-sizing, self-centering arm 166 helps to keepthe OTW valvulotome 100 centered in a vein, allowing for less trauma andmore effective valve cutting. The size of the hoops 166 and blades 164adjust to the internal diameter of a vein as the OTW valvulotome 100 isbeing drawn through a vessel, thus one size cutting unit 120 allows foreffective valve disruption through a wide range of vein diameters. In anembodiment, a thin walled band is suaged or bonded to the catheter 140,for attaching the first end 168 of each of the cutting tools 160 inplace. In an embodiment, the thin walled band is manufactured from ametal material. In an embodiment, the thin walled band is manufacturedfrom a plastic material. In an embodiment, the thin walled band ismanufactured from a stainless steel material. In an embodiment, catheter140 is welded or soldered to each end 168. In an embodiment, thecatheter 140 may be abraided or laser-ablated to aid the bond. Thesecond end 162 of each cutting tool 160 is free to float up and downwithin the body of the atraumatic tip 112, and are guided by slots 222located within the body of the retainer 132, see FIG. 5 in conjunctionwith FIGS. 6A and 6B. In an embodiment, the slots 222 areaxially-oriented slots arranged circumferentially around the retainer132 at roughly 90° from each other. The OTW valvulotome 100 issufficiently designed with space constraints in mind, while notsacrificing the self-centering, self-sizing and cutting efficacybehavior of the centering hoops 166/blades 164, the column strength andflexibility of the catheter 140/sheath 170, and the robustness of thedevice 100.

In an embodiment, the retainer 132 is manufactured from a polymermaterial. In an embodiment, the retainer 132 is manufactured from ametal material. In an embodiment, the retainer 132 is manufactured froma stainless steel material. In an embodiment, the retainer 132 ismanufactured from a molded part. The retainer 132 can be manufacturedfrom any material that provides the necessary strength requirements tobe manipulated in situ, and maintain the cutting blades 164 of thecutting tools 160 in position during actuation of the device. Theretainer 132 acts as a shelter or garage accommodating the cuttingblades 164 of the cutting tools 160. In the abandon or closed position,the cutting blades 164 are encased in the retainer portion 132. Thesecond ends 162 inside atraumatic tip 112 are prevented from exiting theretainer 132 via a hooked head at the distal end of the cutting blades164, which are prevented from moving past stop positions 262 in theretainer 132.

In an embodiment, the arm 166 is a flat spring section with resiliencythat is sufficiently designed to automatically adjust to differentdiameter veins. As illustrated in FIGS. 6A and 6B in conjunction withFIG. 7, which shows a cutaway view along line 7-7 of FIG. 6B, a neck 167of the arm 166 is radially bent/shaped in such a way as to accommodatethe catheter 140 underneath and the sheath 170 (not illustrated)overtop. The sheath 170 is slidably positioned over the catheter 140 toretract or sheath the cutting tools 160. In the abandon position, thecutting blades 164 of the cutting unit 120 sit inside the slots 222 ofretainer 132. The sheath 170 enables smooth passage of the valvulotome100 by closing the centering arms 166 of each of the cutting tools 160,thereby parking the cutting blades 164 in a “blade garage”.

As illustrated in FIG. 4 in conjunction with FIG. 6A, each cutting tool160 is constructed so that the self-sizing, self-centering arm 166extends outward in a radial direction relative to the catheter 140 suchthat, during use, the distance separating the outermost point of eachself-sizing, self-centering arm 166 from the catheter 140 is greaterthan the distance separating the outermost point of each cutting edge165 from the catheter 140. When the sheath 170 is slid off the arms 166,the arms 166 open and the blades 164 come out of the retainer 132 (FIG.6A). The curve of the arm 166 opens farther away from the catheter 140than the cutting edge 165 of the blade 164. When the valvulotome 100 isused, the arm 166 apposes the vein wall and prevents the edge 165 of theblade 164 from contacting the wall. The edge 165 of the blade 164 isonly allowed to contact valves (to cut them). The arms 166 prevent theedge 165 of the blades 164 from cutting the vein wall. As theself-centering arms 166 adjusts to the internal diameter of the vein,the size of the cutting edge 165 is also being adjusted, so as toprevent vein wall trauma. Each cutting blade 164 has an upper,non-cutting outermost edge shielding the cutting edge 165 disposedinwardly therefrom relative to the catheter 140 such that the cuttingedge 165 is oriented toward the proximal end of the self-centeringvalvulotome 100 having a pull handle.

FIG. 8 shows a perspective exploded view of the OTW valvulotome 100 withan alternative embodiment of a retainer at the distal end thereof. Asillustrated in FIG. 8, the distal end of the catheter 140, which, inFIG. 8 is not shown as being laser-cut, is positioned within a proximalend of the body of a retainer 332. The retainer 332 includes slots 322,that serve the same function as slots 222 described above. The secondends 162 are prevented from exiting the retainer 332 via the hooked headat the distal end of the cutting blades 164, which are prevented frommoving past stop positions 362 in the retainer 332. A proximal end ofthe hypotube 122 is positioned within a distal end of the body of theretainer 332, and a distal end of the hypotube 122 can be partially orcompletely disposed within the atraumatic tip 112. In an embodiment, thecatheter 140, the retainer 332, and the hypotube 122 are separate piecesthat can be seam-welded, face-welded, butt-welded, spot-welded,soldered, adhesive bonded, chemically bonded or mechanically fastenedtogether. The catheter 140, the retainer 332, and the hypotube 122, whenengaged, form a continuous internal channel, allowing the OTWvalvulotome 100 to be advanced over a guidewire. In an embodiment, theinternal channel amounts to half the cross-sectional area of the distalportion of the OTW valvulotome 100, without a substantial change to theouter diameter. The guidewire would run coaxially through the catheter140, the retainer 332, the hypotube 122 and the atraumatic tip 112. Allother features of the valvulotome 100, including the cutting unit 120and control mechanism 180 are as described above.

FIG. 9 shows a perspective exploded view of the OTW valvulotome 100 withan alternative embodiment of a retainer at the distal end thereof. Asillustrated in FIG. 9, the distal end of the catheter 140 engages aproximal end of the hypotube 122, wherein a retainer 432 surrounds thehypotube 122. The retainer 432 includes slots 422, that serve the samefunction as slots 222 and 322 described above. The second ends 162 areprevented from exiting the retainer 432 via the hooked head at thedistal end of the cutting blades 164, which are prevented from movingpast stop positions 462 in the retainer 432. In an embodiment, thehypotube 122 and the retainer 432 are manufactured as a single unit. Inan embodiment, the hypotube 122 and the retainer 432 are manufacturedfrom two separate components. In an embodiment, the retainer 432 is amolded part. In an embodiment, the retainer 432 is insert-molded to asection of the hypotube 122. In an embodiment, the retainer 432 is aseparate molded part that is bonded to the hypotube 122. In anembodiment, the hypotube 122 is manufactured from a metal material. Inan embodiment, the catheter 140 is bonded to the hypotube 122 justproximal the retainer portion 432. Although not illustrated, in anembodiment, the atraumatic tip 112 is incorporated at the distal end ofthe hypotube 122. In an embodiment, the catheter 140 and the hypotube122 are separate pieces that can be seam-welded, face-welded,butt-welded, spot-welded, soldered, adhesive bonded, chemically bondedor mechanically fastened together. The catheter 140 and the hypotube122, when engaged, form a continuous internal channel, allowing the OTWvalvulotome 100 to be advanced over a guidewire. In an embodiment, theinternal channel amounts to half the cross-sectional area of the distalportion of the OTW valvulotome 100, without a substantial change to theouter diameter. The guidewire would run coaxially through the catheter140 and the hypotube 122. All other features of the valvulotome 100,including the cutting unit 120 and control mechanism 180 are asdescribed above.

FIG. 10 shows a perspective view of an alternative embodiment of acombination retainer/atraumatic tip 532 for use at the distal end of theOTW valvulotome of FIGS. 1A and 2A. The retainer/atraumatic tip 532 hasan inside square profile 530, thus requiring no slots, in contrast tothe slots 222 in retainer 132. The retainer/atraumatic tip 532 isconfigured to act as both an traumatic tip as well as a garage for thecutting blades 164. In an embodiment, the retainer/atraumatic tip 532helps to orient the cutting blades 164 correctly. In an embodiment, thecutting blades 164 of the cutting tools 160 would come out the back-endof the retainer/atraumatic tip 532 hybrid (as the sheath 170 is removed)and then open sideways. In an embodiment, slots are designed into theretainer/atraumatic tip 532, thus the cutting blades 164 would come outfrom the side, as illustrated in FIG. 6B.

In an embodiment, an over-the-wire self-sizing, self-centeringexpandable valvulotome of the present disclosure includes a catheterhaving a proximal end, a distal end, and a longitudinal axistherebetween, wherein a first portion of a plurality of cutting toolsengage the catheter at the distal end, and wherein an actuationmechanism engages the catheter at the proximal end; a retainer forengaging a second portion of the plurality of cutting tools, wherein thesecond portion includes cutting blades; and a sheath slidably moveableover the plurality of cutting blades, wherein the catheter and theretainer have internal diameters configured for passing over aguidewire. In an embodiment, the actuation mechanism includes a handleportion and an irrigation port. In an embodiment, the handle portion issufficiently designed to control the positioning of the sheath relativeto the plurality of cutting blades. In an embodiment, the retainer issufficiently designed to function as an atraumatic tip. In anembodiment, the valvulotome further includes an atraumatic tip. In anembodiment, the valvulotome further comprises an atraumatic tip. In anembodiment, the plurality of cutting tools are radially mounted to boththe catheter and the retainer. In an embodiment, between the first endand the second end of each cutting tool is a self-sizing, self-centeringarm or hoop.

In an embodiment, an over-the-wire self-sizing, self-centeringexpandable valvulotome of the present disclosure includes a protectivesheath having a lumen; a catheter having a catheter lumen, a distalportion, and a proximal portion, the catheter being partly and slidablydisposed within the protective sheath; a retainer having a retainerlumen and at least four slots, the retainer fixedly engaging the distalportion of the catheter so as to provide a continuous internal channelfor a guidewire; a self-sizing, self-centering cutting unit having atleast four cutting tools, wherein each cutting tool comprises: a firstend fixedly engaged to the distal portion of the catheter; a second endmoveably positioned within and guided by the slot of the retainer, thesecond end having a cutting blade with a recessed cutting edge; aself-sizing, self-centering resilient arm connecting the first end withthe second end; and a radially bent shaped neck transitioning betweenthe arm and the second end, the neck sufficiently designed toaccommodate an outer circumference of the catheter; and a dual-purposecontrol mechanism attached to the protective sheath's proximal end andallowing the passage therethrough of the catheter, such that a user ofthe valvulotome can sheathe and unsheathe the cutting tools by slidingthe catheter distally or proximally relative to the protective sheath.

In an embodiment, a method of performing a valvulotomy procedure usingan over-the-wire self-sizing, self-centering valvulotome of the presentdisclosure includes the following procedure: a surgeon places aguidewire in a saphenous vein of a patient to aid in navigation, whereinthe guidewire is thought to be an aid when navigating branching veinsystems or tortuous saphenous veins; once the proximal end of thesaphenous vein has been sutured to the femoral artery, the over-the-wireself-sizing, self-centering valvulotome of the present disclosure, withthe cutting blades in a closed sheathed position, is inserted over theguidewire into the distal opening of the vein and advanced to the mostproximal segment of the vein; the cutting blades of the valvulotome areopened by slidably moving the sheath relative to the catheter; thevalvulotome is withdrawn caudad to excise the valves; the guidewire isleft in its original position in the event that a second valvulotomepass is needed; following valvulotomy the distal end of the vein issutured to the recipient artery and blood is once again able to flow tothe foot. Thus the surgeon has “bypassed” the arterial blockage andre-delivered blood to the foot. During use, the construction of thecutting tools is such that the venous valve is opened upon insertion ofthe valvulotome, but that the vein's natural bloodflow is allowed toclose the valve once the cutting tool has passed through, maximizing thedestruction of the valve flaps when the cutting tool is withdrawnthrough the valve.

In an embodiment, a method of performing a valvulotomy procedureincludes accessing the vein at both a distal and a proximal point andplacing a guidewire in the vein to aid in navigation; inserting anover-the-wire self-sizing, self-centering valvulotome over the guidewireand into the vein at its distal access point, wherein the valvulotomecomprises: a catheter having a proximal end, a distal end, and alongitudinal axis therebetween, wherein a first portion of a pluralityof cutting tools engage the catheter at the distal end, and wherein anactuation mechanism engages the catheter at the proximal end; a retainerfor temporarily shielding a second portion of the plurality of cuttingtools, wherein the second portion includes cutting blades; and a sheathslidably moveable over the plurality of cutting blades; feeding thevalvulotome into the vein with the cutting unit sheathed, until thecutting unit is past a most proximal valve in the vein; manipulating theactuation mechanism to unsheath the cutting unit to release the cuttingblades; and withdrawing the valvulotome from the vein, thereby severingeach valve in the vein.

In an embodiment, a method of performing a valvulotomy procedure usingan over-the-wire self-sizing, self-centering valvulotome of the presentdisclosure includes selecting a suitable vein for the procedure;accessing the vein at both a distal and a proximal point and segmentingthe vein; placing a guidewire in the vein to aid in navigation;inserting an over-the-wire self-sizing, self-centering valvulotome overthe guidewire and into the vein segment at its distal access point,wherein the valvulotome comprises: a catheter having a catheter lumen, adistal portion, and a proximal portion; a retainer having a retainerlumen and at least four slots, the retainer fixedly engaging the distalportion of the catheter so as to provide a continuous internal channelfor the guidewire; and a self-sizing, self-centering cutting unit havingat least four cutting tools, wherein each cutting tool has a first endfixedly engaged to the distal portion of the catheter, a second endmoveably positioned within and guided by the slot of the retainer, thesecond end having a cutting blade with a recessed cutting edge, aself-sizing, self-centering resilient arm connecting the first end withthe second end, and a radially bent shaped neck transitioning betweenthe arm and the second end, the neck sufficiently designed toaccommodate an outer circumference of the catheter; feeding thevalvulotome into the vein segment until the cutting unit is past themost proximal valve in the vein segment; and withdrawing the valvulotomefrom the vein segment, thereby severing each valve in the segment.

All patents, patent applications, and published references cited hereinare hereby incorporated by reference in their entirety. It will beappreciated that various of the above-disclosed and other features andfunctions, or alternatives thereof, may be desirably combined into manyother different systems or applications. Various presently unforeseen orunanticipated alternatives, modifications, variations, or improvementstherein may be subsequently made by those skilled in the art which arealso intended to be encompassed by the following claims.

what is claimed is:
 1. An over-the-wire valvulotome comprising: acatheter having an internal catheter diameter, wherein the internalcatheter diameter is sized for passing a guidewire therethrough; acutting unit disposed at a distal portion of the catheter and comprisinga plurality of self-centering, self-sizing cutting tools having acutting blade with a cutting edge on an arm between a first end and asecond end of the cutting unit, and an atraumatic tip at a distal end ofthe valvulotome, wherein each cutting tool is designed so when thecutting unit is in a closed position, a portion of each cutting tool ispositioned adjacent to an outer circumference of the catheter.
 2. Thevalvulotome of claim 1 further comprising an actuation mechanism locatedat the proximal end of the catheter.
 3. The valvulotome of claim 2wherein the actuation mechanism includes a handle portion and anirrigation port.
 4. The valvulotome of claim 1 further comprising asheath slidably moveable over the plurality of cutting blades.
 5. Thevalvulotome of claim 1 wherein the cutting blade has an upper,non-cutting outermost edge shielding the cutting edge.
 6. Thevalvulotome of claim 1 wherein the cutting edge is oriented toward aproximal end of the valvulotome.
 7. The valvulotome of claim 1 whereinthe arm is radially bent to accommodate the outer circumference of thecatheter.
 8. The valvulotome of claim 1 wherein the arm is a flat springwith resiliency to automatically adjust to a diameter of a vein.
 9. Anover-the-wire valvulotome comprising: a sheath having a lumen; acatheter having an internal catheter diameter, wherein the internalcatheter diameter is sized for passing a guidewire through, the catheterbeing partly and slidably disposed within the sheath; a cutting unitdisposed at a distal portion of the catheter and comprising at least twoself-centering, self-sizing cutting tools having a cutting blade with acutting edge on an arm between a first end and a second end of thecutting unit, and wherein each cutting tool is designed so when thecutting unit is in a closed position, a portion of each cutting toolclosely surrounds an outer circumference of the catheter; and anatraumatic tip.
 10. The valvulotome of claim 9 further comprising adual-purpose control mechanism attached to a proximal end of the sheathand allowing the passage therethrough of the catheter, such that a userof the valvulotome can sheathe and unsheathe the cutting tools bysliding the catheter distally or proximally relative to the sheath. 11.The valvulotome of claim 10 wherein the dual-purpose control mechanismcomprises a valve segment having a terminal end and an upper end, thevalve segment being disposed partly within the proximal end of thesheath and the terminal end of the valve segment being adapted to allowengagement of a pull handle attached to the proximal end of thecatheter.
 12. The valvulotome of claim 11 wherein the upper end of thevalve has an access port.
 13. The valvulotome of claim 12 wherein thepull handle engages the terminal end of the valve segment to create afluid-tight seal, thereby allowing the introduction or removal of adiagnostic or therapeutic fluid to the distal end of the sheath via thevalve access port and the lumen of the sheath.
 14. The valvulotome ofclaim 9 wherein the cutting blade has an upper, non-cutting outermostedge shielding the cutting edge.
 15. The valvulotome of claim 9 whereinthe cutting edge is oriented toward a proximal end of the valvulotome.16. The valvulotome of claim 9 wherein the arm is radially bent toaccommodate the outer circumference of the catheter.
 17. The valvulotomeof claim 9 wherein the arm is a flat spring with resiliency toautomatically adjust to a diameter of a vein.
 18. A method of performinga valvulotomy procedure comprising: inserting a valvulotome over aguidewire and into a vein, wherein the valvulotome comprises: a catheterhaving an internal catheter diameter, wherein the internal catheterdiameter is sized for passing a guidewire therethrough; a cutting unitdisposed at a distal portion of the catheter and comprising a pluralityof self-centering, self-sizing cutting tools having a cutting blade witha cutting edge on an arm between a first end and a second end of thecutting unit, and wherein each cutting tool is designed so when thecutting unit is in a closed position, a portion of each cutting tool ispositioned near an outer circumference of the catheter, feeding thevalvulotome into the vein with the cutting unit sheathed; unsheathingthe cutting unit to release the cutting blades; and withdrawing thevalvulotome from the vein, thereby severing at least one valve in thevein.
 19. The method of claim 18 further comprising manipulating anactuation mechanism to allow the cutting blades to automatically biasagainst a vein wall.
 20. The method of claim 18 for use in cuttingvalves through various vein diameters.